I haven't done one camera and one lens for a year, but I did do one camera, one lens, and one film for a trip.
My wife and I went to Italy for a week last year, trips are normally where I bring a few cameras and films. This time, I wanted to try to limit myself, so I brought my 501c, 80mm, and berggerpancro 400, nothing else. I think, overall, it was a pretty good experience.
I have a friend who shoots a leica mp, that is all he shoots, all I've ever known him to shoot, he has really motivated me to try to pare down gear to a few cameras. I'd like to get to what I call the Tim Hetherington kit: Hasselblad and Rolleiflex.